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ACP-WG-S/4 WP-10 Revision1
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International Civil Aviation Organization
WORKING PAPER / ACP-WG-S/4WP-10 Revision 1
16/10/2013

AERONAUTICAL COMMUNICATIONS PANEL (ACP)

FourthMeeting of theSurface Datalink Working Group

Montreal, Canada15-17October2013

Agenda Item 5.1: / Review of AeroMACS SARPs

Status of Action #3-12: Discussion on integrity section for AeroMACS SARPs

Presented by the ECTL

SUMMARY
This paperprovides the current status of the action item #3-12 about the development of a proposal for the integrity section of the AeroMACS SARPs.
ACTION
The AeroMACS Working Group is invited to note the proposal and provide feedback in order to finalise the proposal or decide the way ahead.

1.Introduction:

1.1In the WGS/3 meeting the integrity section (section 4.4.1) was reviewed. As the origin of the proposed requirement (residual error rate less than or equal to 5 x 10-8per SNSDU) in the then (as of WGS/3) version of the SARPs was not clear, it was requested (action 3-12) to investigate what should be the integrity requirements and make a proposal for discussion in WGS.

1.2This paper provides the outcome of the investigations. The work consisted of:

  • researching for integrity related requirements of the existing SARPs of other ICAO systems
  • researching for integrity related requirements on AeroMACS related work (such as MASPs, IEEE 802.16 standard, Draft SESAR AeroMACS deliverables
  • Developing a proposal for discussion in the WGS

2.Integrity Information in SARPs of existing ICAO Systems

2.1Annex 10 Volume 3 was searched for integrity related information. In summary, the SATCOM, Mode S, VDLs and HF data link systems do have some integrity related information, usually in the form of (bit) error rate requirements. UAT does not have error rate requirements but a description of the capabilities of the error correcting scheme employed (RS codes) is provided.

2.2Appendix A provides the Annex 10 material relating to integrity requirementsfor existing systems.

3.Integrity requiremenTS Proposal for discussion

3.1This section identifies a proposal for the integrity section (4.x.y) for discussion and finalisation in the WGS/4 meeting.

4.x.1AeroMACS BS and MS shall support mechanisms to detect and correct corrupt SNSDUs .

4.x.2The AeroMACS BS and MS shall only process SNSDUs addressed to itself.

4.x.3Recommendation:The residual error rate, to/from MS should be less than or equal to 5 x 10-8 per SNSDU.

Note: There are no integrity requirements for SNSDU residual rate to the BS and M as the requirement is entirely satisfied by the end-to-end systems in the aircraft and Air Traffic Service Provider.

4.x.5The maximum bit error rate shall not exceed 10-6after FEC assuming a minimum received signal equal to the corresponding sensitivity level.

4.ACTION BY THE MEETING

4.1The AeroMACS Working Group is invited to note the proposal and provide feedback in order to finalise the proposal or decide the way ahead.

5.Appendix A

5.1AMS(R)S SARPS Integrity Information (Annex 10, V3, Ch4)

4.6.4.1.3 INTEGRITY

4.6.4.1.3.1 Residual error rate, from-aircraft. The residual error rate in the from-aircraft direction shall not be greater than 10-4 per SNSDU.

4.6.4.1.3.1.1 Recommendation.— The residual error rate in the from-aircraft direction should not be greater than10-6 per SNSDU.

4.6.4.1.3.2 Residual error rate, to-aircraft. The residual error rate in the to-aircraft direction shall not be greater than 10-6 per SNSDU.

4.6.4.1.3.3 Connection resilience. The probability of a subnetwork connection (SNC) provider-invoked SNC release shall not be greater than 10-4 over any one-hour interval.

Note.— Connection releases resulting from GES-to-GES handover, AES log-off or virtual circuit pre-emption are excluded from this specification.

4.6.4.1.3.4 The probability of an SNC provider-invoked reset shall not be greater than 10-1 over any one-hour interval.

5.2Mode S SARPS Integrity Information (Annex 10, V3, Ch5)

5.2.11 System requirements

5.2.11.1 Data integrity. The maximum bit error rates for data presented at the ADLP/transponder interface or the GDLP/interrogator interface measured at the local DTE/XDLP interface (and vice versa) shall not exceed 10-9 for undetected errors and 10-7 for detected errors.

Note.— The maximum error rate includes all errors resulting from data transfers across the interfaces and from XDLP internal operation.

5.3VDLs SARPS Integrity Information (Annex 10, V3, Ch6)

6.3.5 Receiving function

6.3.5.1 Specified error rate. The specified error rate for Mode 2 operation shall be the maximum corrected Bit Error Rate (BER) of 1 in 104. The specified error rate for Mode 3 operation shall be the maximum uncorrected BER of 1 in 103. The specified error rate for Mode 4 operation shall be the maximum uncorrected BER of 1 in 104.

Note.— The above physical layer BER requirements are derived from the BER requirement imposed by ATN at the subnetwork interface.

5.4HF SARPS Integrity Information (Annex 10, V3, Ch11)

11.2.6.1 RESIDUAL PACKET ERROR RATE

The undetected error rate for a network user packet which contains between 1 and 128 octets of user data shall be equal to or less than 1 in 106.

5.5UAT SARPS Integrity Information (Annex 10, V3, Ch12)

12.4.4.1.3.1 Code type

The FEC parity generation shall be based on a systematic Reed-Solomon (RS) 256-ary code with 8-bit code word symbols.

FEC parity generation shall be per the following code:

a) Basic UAT ADS-B message: Parity shall be a RS (30, 18) code.

Note.— This results in 12 bytes (code symbols) of parity capable of correcting up to 6 symbol errors per block.

b) Long UAT ADS-B message: Parity shall be a RS (48, 34) code.

Note.— This results in 14 bytes (code symbols) of parity capable of correcting up to 7 symbol errors per block